I've noticed T-stats are not what they used to be as well.

As for the temp rating, thats the rating that the t-stat is supposed to keep the engine. Not necessarily when it should open.
The t-stat will start opening way before that, otherwise you'd get the old fluctuation thing where the temp gauges keeps pegging both ways cause the t-stat is opening and closing so much.

They are pretty neat.
Play with one in a frying pan and with a lighter or torch.

It's just a liquid medium like wax inside that when it heats it forces the t-stat to open.